With the increased technological development and demands for a mobile device, demands for a secondary battery as energy source has rapidly increased. A nickel-cadmium battery or a hydrogen ion battery, which was used as a secondary battery in the past, has recently been increasingly replaced by a lithium ion battery and a polymer lithium ion battery having high energy density.
A lithium secondary battery using lithium complex oxide, and so on, which has high power and capacity relative to weight is receiving increasing attention for its use as a positive electrode active material of the secondary battery. Generally, the lithium secondary battery has a structure in which an electrode assembly of a positive electrode/separator/negative electrode structure and an electrolyte is embedded in a sealed container.
Meanwhile, the lithium secondary battery is composed of a positive electrode, a negative electrode, a separator interposed therebetween, and the electrolyte. Further, the lithium secondary battery may be categorized into the lithium ion battery (LIB), the polymer lithium ion battery (PLIB), and so on, according to materials used for a positive electrode active material and a negative electrode active material. In a related art, the electrode of the lithium secondary battery may be formed by coating the positive electrode active material or negative electrode active material on a current collector such as aluminum or copper sheet, mesh, film, foil, and so on, and drying the same.
Generally, it is a hard task to configure the secondary battery module to be compact. However, even when the module is configured to be compact, since a separate mounting structure should be applied so as to assemble into a pack, even with the modules of high energy density, forming the separate modules into a pack involves a problem of reduced energy density of the whole pack.